/**
 * Copyright 2009-2020 the original author or authors.
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.ibatis.builder.annotation;

import org.apache.ibatis.annotations.Lang;
import org.apache.ibatis.builder.BuilderException;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.SqlSource;
import org.apache.ibatis.reflection.ParamNameResolver;
import org.apache.ibatis.scripting.LanguageDriver;
import org.apache.ibatis.session.Configuration;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Map;

/**
 * @author Clinton Begin
 * @author Kazuki Shimizu
 */
public class ProviderSqlSource implements SqlSource {

	private final Configuration configuration;
	private final Class<?> providerType;
	private final LanguageDriver languageDriver;
	private final Method mapperMethod;
	private final Method providerMethod;
	private final String[] providerMethodArgumentNames;
	private final Class<?>[] providerMethodParameterTypes;
	private final ProviderContext providerContext;
	private final Integer providerContextIndex;

	/**
	 * This constructor will remove at a future version.
	 *
	 * @param configuration
	 *          the configuration
	 * @param provider
	 *          the provider
	 * @deprecated Since 3.5.3, Please use the {@link #ProviderSqlSource(Configuration, Annotation, Class, Method)}
	 *             instead of this.
	 */
	@Deprecated
	public ProviderSqlSource(Configuration configuration, Object provider) {
		this(configuration, provider, null, null);
	}

	/**
	 * This constructor will remove at a future version.
	 *
	 * @param configuration
	 *          the configuration
	 * @param provider
	 *          the provider
	 * @param mapperType
	 *          the mapper type
	 * @param mapperMethod
	 *          the mapper method
	 * @since 3.4.5
	 * @deprecated Since 3.5.3, Please use the {@link #ProviderSqlSource(Configuration, Annotation, Class, Method)} instead of this.
	 */
	@Deprecated
	public ProviderSqlSource(Configuration configuration, Object provider, Class<?> mapperType, Method mapperMethod) {
		this(configuration, (Annotation) provider, mapperType, mapperMethod);
	}

	/**
	 * Instantiates a new provider sql source.
	 *
	 * @param configuration
	 *          the configuration
	 * @param provider
	 *          the provider
	 * @param mapperType
	 *          the mapper type
	 * @param mapperMethod
	 *          the mapper method
	 * @since 3.5.3
	 */
	public ProviderSqlSource(Configuration configuration, Annotation provider, Class<?> mapperType, Method mapperMethod) {
		String candidateProviderMethodName;
		Method candidateProviderMethod = null;
		try {
			this.configuration = configuration;
			this.mapperMethod = mapperMethod;
			Lang lang = mapperMethod == null ? null : mapperMethod.getAnnotation(Lang.class);
			this.languageDriver = configuration.getLanguageDriver(lang == null ? null : lang.value());
			this.providerType = getProviderType(configuration, provider, mapperMethod);
			candidateProviderMethodName = (String) provider.annotationType().getMethod("method").invoke(provider);

			if (candidateProviderMethodName.length() == 0 && ProviderMethodResolver.class.isAssignableFrom(this.providerType)) {
				candidateProviderMethod = ((ProviderMethodResolver) this.providerType.getDeclaredConstructor().newInstance())
						.resolveMethod(new ProviderContext(mapperType, mapperMethod, configuration.getDatabaseId()));
			}
			if (candidateProviderMethod == null) {
				candidateProviderMethodName = candidateProviderMethodName.length() == 0 ? "provideSql" : candidateProviderMethodName;
				for (Method m : this.providerType.getMethods()) {
					if (candidateProviderMethodName.equals(m.getName()) && CharSequence.class.isAssignableFrom(m.getReturnType())) {
						if (candidateProviderMethod != null) {
							throw new BuilderException("Error creating SqlSource for SqlProvider. Method '"
									+ candidateProviderMethodName + "' is found multiple in SqlProvider '" + this.providerType.getName()
									+ "'. Sql provider method can not overload.");
						}
						candidateProviderMethod = m;
					}
				}
			}
		} catch (BuilderException e) {
			throw e;
		} catch (Exception e) {
			throw new BuilderException("Error creating SqlSource for SqlProvider.  Cause: " + e, e);
		}
		if (candidateProviderMethod == null) {
			throw new BuilderException("Error creating SqlSource for SqlProvider. Method '"
					+ candidateProviderMethodName + "' not found in SqlProvider '" + this.providerType.getName() + "'.");
		}
		this.providerMethod = candidateProviderMethod;
		this.providerMethodArgumentNames = new ParamNameResolver(configuration, this.providerMethod).getNames();
		this.providerMethodParameterTypes = this.providerMethod.getParameterTypes();

		ProviderContext candidateProviderContext = null;
		Integer candidateProviderContextIndex = null;
		for (int i = 0; i < this.providerMethodParameterTypes.length; i++) {
			Class<?> parameterType = this.providerMethodParameterTypes[i];
			if (parameterType == ProviderContext.class) {
				if (candidateProviderContext != null) {
					throw new BuilderException("Error creating SqlSource for SqlProvider. ProviderContext found multiple in SqlProvider method ("
							+ this.providerType.getName() + "." + providerMethod.getName()
							+ "). ProviderContext can not define multiple in SqlProvider method argument.");
				}
				candidateProviderContext = new ProviderContext(mapperType, mapperMethod, configuration.getDatabaseId());
				candidateProviderContextIndex = i;
			}
		}
		this.providerContext = candidateProviderContext;
		this.providerContextIndex = candidateProviderContextIndex;
	}

	@Override
	public BoundSql getBoundSql(Object parameterObject) {
		SqlSource sqlSource = createSqlSource(parameterObject);
		return sqlSource.getBoundSql(parameterObject);
	}

	private SqlSource createSqlSource(Object parameterObject) {
		try {
			String sql;
			if (parameterObject instanceof Map) {
				int bindParameterCount = providerMethodParameterTypes.length - (providerContext == null ? 0 : 1);
				if (bindParameterCount == 1
						&& providerMethodParameterTypes[Integer.valueOf(0).equals(providerContextIndex) ? 1 : 0].isAssignableFrom(parameterObject.getClass())) {
					sql = invokeProviderMethod(extractProviderMethodArguments(parameterObject));
				} else {
					@SuppressWarnings("unchecked")
					Map<String, Object> params = (Map<String, Object>) parameterObject;
					sql = invokeProviderMethod(extractProviderMethodArguments(params, providerMethodArgumentNames));
				}
			} else if (providerMethodParameterTypes.length == 0) {
				sql = invokeProviderMethod();
			} else if (providerMethodParameterTypes.length == 1) {
				if (providerContext == null) {
					sql = invokeProviderMethod(parameterObject);
				} else {
					sql = invokeProviderMethod(providerContext);
				}
			} else if (providerMethodParameterTypes.length == 2) {
				sql = invokeProviderMethod(extractProviderMethodArguments(parameterObject));
			} else {
				throw new BuilderException("Cannot invoke SqlProvider method '" + providerMethod
						+ "' with specify parameter '" + (parameterObject == null ? null : parameterObject.getClass())
						+ "' because SqlProvider method arguments for '" + mapperMethod + "' is an invalid combination.");
			}
			Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();
			return languageDriver.createSqlSource(configuration, sql, parameterType);
		} catch (BuilderException e) {
			throw e;
		} catch (Exception e) {
			throw new BuilderException("Error invoking SqlProvider method '" + providerMethod
					+ "' with specify parameter '" + (parameterObject == null ? null : parameterObject.getClass()) + "'.  Cause: " + extractRootCause(e), e);
		}
	}

	private Throwable extractRootCause(Exception e) {
		Throwable cause = e;
		while (cause.getCause() != null) {
			cause = cause.getCause();
		}
		return cause;
	}

	private Object[] extractProviderMethodArguments(Object parameterObject) {
		if (providerContext != null) {
			Object[] args = new Object[2];
			args[providerContextIndex == 0 ? 1 : 0] = parameterObject;
			args[providerContextIndex] = providerContext;
			return args;
		} else {
			return new Object[]{parameterObject};
		}
	}

	private Object[] extractProviderMethodArguments(Map<String, Object> params, String[] argumentNames) {
		Object[] args = new Object[argumentNames.length];
		for (int i = 0; i < args.length; i++) {
			if (providerContextIndex != null && providerContextIndex == i) {
				args[i] = providerContext;
			} else {
				args[i] = params.get(argumentNames[i]);
			}
		}
		return args;
	}

	private String invokeProviderMethod(Object... args) throws Exception {
		Object targetObject = null;
		if (!Modifier.isStatic(providerMethod.getModifiers())) {
			targetObject = providerType.getDeclaredConstructor().newInstance();
		}
		CharSequence sql = (CharSequence) providerMethod.invoke(targetObject, args);
		return sql != null ? sql.toString() : null;
	}

	private Class<?> getProviderType(Configuration configuration, Annotation providerAnnotation, Method mapperMethod)
			throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
		Class<?> type = (Class<?>) providerAnnotation.annotationType().getMethod("type").invoke(providerAnnotation);
		Class<?> value = (Class<?>) providerAnnotation.annotationType().getMethod("value").invoke(providerAnnotation);
		if (value == void.class && type == void.class) {
			if (configuration.getDefaultSqlProviderType() != null) {
				return configuration.getDefaultSqlProviderType();
			}
			throw new BuilderException("Please specify either 'value' or 'type' attribute of @"
					+ providerAnnotation.annotationType().getSimpleName()
					+ " at the '" + mapperMethod.toString() + "'.");
		}
		if (value != void.class && type != void.class && value != type) {
			throw new BuilderException("Cannot specify different class on 'value' and 'type' attribute of @"
					+ providerAnnotation.annotationType().getSimpleName()
					+ " at the '" + mapperMethod.toString() + "'.");
		}
		return value == void.class ? type : value;
	}

}
